Saddle stitched booklets typically contain 100 pages or less; that is, 100 booklet pages produced from 25 sheets of paper, each page printed duplex with two page images on each side of each sheet. The 100 page limitation comes from the sharpness of the fold and the ability of staples to penetrate the stack of sheets.
In the past saddle stitched booklets were produced by processing the entire booklet at once. Referring to FIG. 1, reference numeral 10 generally indicates a stack of duplex printed sheets, arranged in order for binding. The sheets underlay each other and are squared off in registration. One or more staples 12 are driven along the center line 11 of the stack 10 of sheets. After the sheets are stapled, the entire stack is folded along the line formed by the staples. Once folded, the free ends of the sheets form two beveled edges 14, FIG. 2 because the outer sheets must wrap around the inner sheets. The inner sheets stick out and the outer sheets and cover, if any, appear to be shorter. Traditionally, the entire booklet is next trimmed inboard of the edge of the cover because the cover or the outermost sheet is the shortest sheet due to its having the longest wrap length. A heavy duty cutting apparatus 15 performs this trimming operation because the cut must be made through the entire booklet typically 10 to 50 or more sheets. Reference numeral 16 generally indicates a finished, saddle stitched booklet with a finished, flat edge 17.
The prior machines for making saddle stitched booklets typically require long paper paths, powerful motors, heavy and complex cutters, high electrical current, and heavy bracing to withstand high mechanical forces. These prior machines are also bulky, expensive, require a skilled operator, and are therefore ill suited for home and small office use. These machines are typically found only in commercial document production installations.
Thus, it can be seen from the foregoing that prior paper finishing techniques impose size, cost, and power limits upon booklet making devices that hinder the use of these devices in many applications.
Therefore, there has been an unresolved need for a paper finishing apparatus and method that permit the production of booklets using a low-power device that is both inexpensive and compact.